A known technology as a variable valve timing control device is disclosed in JPH09-177519A (hereinafter referred to as Patent reference 1). According to Patent reference 1, the variable valve timing control device (a variable valve timing control mechanism in Patent reference 1) is disposed such that a part thereof is submerged at an operating fluid reservoir being provided at a cylinder head of an internal combustion engine.
In Patent reference 1, an advanced-angle chamber and a retarded-angle chamber (a first oil hydraulic chamber and a second oil hydraulic chamber in Patent reference 1) are formed by a vane that defines each of plural pressure chambers. When the internal combustion engine stops, one of the advanced-angle chamber and the retarded-angle chamber that is submerged in the operating fluid reservoir inhibits the operating oil from leaking thereout.
A known technology including an oil hydraulic control valve selectively supplying operating oil to an advanced-angle chamber and a retarded-angle chamber is disclosed in JP2001-200709A (hereinafter referred to as Patent reference 2). The technology includes an operating oil reservoir accumulating the operating oil at a passage to which the operating oil is discharged when the operating oil is supplied to one of the advanced-angle chamber and the retarded-angle chamber from the oil hydraulic control valve.
In Patent reference 2, when a phase changes in a state where supply pressure of the operating oil is not sufficiently provided, air is inhibited from being sucked into one of the advanced-angle chamber and the retarded-angle chamber by returning the operating oil in the operating oil reservoir to one of the advanced-angle chamber and the retarded-angle chamber via the discharging passage.
In the variable valve timing control devices inhibiting the air from entering into one of the advanced-angle chamber and the retarded-angle chamber as disclosed in Patent reference 1 and Patent reference 2, for example, even in a case where the internal combustion engine that has stopped for a long time starts, air does not enter into one of the advanced-angle chamber and the retarded-angle chamber, and contact noise generated when a vane comes in contact with an end wall of the oil hydraulic chamber in a circumferential direction is inhibited from being generated.
Here, assuming variable valve timing control devices disclosed in JP2012-47228A and JP2012-57578A, each of configurations in which a valve is contained in a bolt connecting a driven side rotational body to a camshaft and in which the valve operates from an opening of a head portion of the bolt is adapted.
In each of the variable valve timing control devices disclosed in JP2012-47228A and JP2012-57578A having such a configuration, because a distance from the valve to one of the advanced-angle chamber and the retarded-angle chamber is short, a control having an enhanced responsiveness is achieved. However, in the variable valve timing control device having this configuration, because the opening of the head portion of the bolt corresponds to a drain portion discharging fluid from the valve, air may be sucked from the head portion of the bolt by a negative pressure generated at one of the advanced-angle chamber and the retarded-angle chamber, and may enter in one of the advanced-angle chamber and the retarded-angle chamber, in a case where the phase displaces in a state where the fluid is not sufficiently provided.
In a case where the air is sucked into one of the advanced-angle chamber and the retarded-angle chamber, the vane may generate contact noise, which is an issue described in Patent reference 1 and Patent reference 2.
A need thus exists for a variable valve timing control device which is not susceptible to the drawback mentioned above.